Remove modules Jamfile: it doesn't work.

Add shell script for testing modules with clang.

.github/workflows/ci.yml

@@ -134,6 +134,41 @@ jobs:
       - name: Test
         run: ../../../b2 toolset=$TOOLSET define=CI_SUPPRESS_KNOWN_ISSUES define=SLOW_COMPILER
         working-directory: ../boost-root/libs/regex/test
+  ubuntu-jammy-clang-18-modules:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: '0'
+      - uses: mstachniuk/ci-skip@v1
+        with:
+          commit-filter: '[skip ci];[ci skip];[CI SKIP];[SKIP CI];***CI SKIP***;***SKIP CI***;[windows];[Windows];[WINDOWS];[apple];[Apple];[APPLE]'
+          commit-filter-separator: ';'
+          fail-fast: true
+      - name: Add repository
+        run: sudo apt-add-repository -y "ppa:ubuntu-toolchain-r/test"
+      - name: Install packages
+        run: sudo apt install clang-18
+      - name: Checkout main boost
+        run: git clone -b develop --depth 1 https://github.com/boostorg/boost.git ../boost-root
+      - name: Update tools/boostdep
+        run: git submodule update --init tools/boostdep
+        working-directory: ../boost-root
+      - name: Copy files
+        run: cp -r $GITHUB_WORKSPACE/* libs/regex
+        working-directory: ../boost-root
+      - name: Install deps
+        run: python tools/boostdep/depinst/depinst.py -I example -g "--jobs 3" regex
+        working-directory: ../boost-root
+      - name: Bootstrap
+        run: ./bootstrap.sh
+        working-directory: ../boost-root
+      - name: Generate headers
+        run: ./b2 headers
+        working-directory: ../boost-root
+      - name: Test
+        run: ./test.sh ./config/clang.sh
+        working-directory: ../boost-root/libs/regex/test/module
   macos:
     runs-on: macos-latest
     strategy: